The mains water supply usually enters a domestic dwelling through a single pipeline, and close to the point of entry a tap (known as a “stop-cock”) is typically provided so that the water supply to the dwelling can be shut-off if required, for example if there is a water leak within the dwelling. The stop-cock is usually located out of sight, and is not always easily accessible, particularly for the elderly or infirm. In addition, the stop-cock may not need to be operated for many years, and might have become seized during that time, so that it is not possible for the dwelling occupier to operate it when it is ultimately required.